SQL stands for structured query language, a high level language for querying relational databases, extracting information.
A Markov chain is a probability system that governs transition among states or through successive events.
MapReduce is a programming framework to distribute the computing load of very large data and problems to multiple computers.
As data processing requirements grew beyond the capacities of even large computers, distributed computing systems were developed to spread the load to multiple computers.
The curse of dimensionality is the affliction caused by adding variables to multivariate data models.